Buried photographer

The murderer is the first person, because all four of them have one thing in common, that is, their right arms are blocked. But all four men's left arms are exposed, and all four men's right arms are exposed a little, so that we can draw the four men's right arms behind the girl according to the direction and length of the arms. According to the drawing results, only the upper left person's right arm is normal. The other three people's right arms are deformed, so it can be inferred that the photos of the other three people are PS, and only the photo of the first person is really taken with the little girl. So the killer was the first.